0.1 second feels instantaneous, like the user's action directly affects whatever is on the screen. This is the ideal.

1 second no longer feels instantaneous, but the user stays focused on the current train of thought. This is acceptable, but not ideal.

10 seconds exceeds the attention span of most users, and they find something else to do. If you're lucky, they let your page load in another tab/window while they do something else. If you aren't lucky, then they leave your site.